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Re: [PATCH 6/6] XFS: Prevent looping in xfs_sync_inodes_ag

To: Dave Chinner <david@xxxxxxxxxxxxx>
Subject: Re: [PATCH 6/6] XFS: Prevent looping in xfs_sync_inodes_ag
From: Christoph Hellwig <hch@xxxxxxxxxxxxx>
Date: Wed, 8 Oct 2008 14:21:38 -0400
Cc: xfs@xxxxxxxxxxx
In-reply-to: <1223416480-7701-7-git-send-email-david@xxxxxxxxxxxxx>
References: <1223416480-7701-1-git-send-email-david@xxxxxxxxxxxxx> <1223416480-7701-7-git-send-email-david@xxxxxxxxxxxxx>
User-agent: Mutt/1.5.18 (2008-05-17)
On Wed, Oct 08, 2008 at 08:54:40AM +1100, Dave Chinner wrote:
> If the last  block of the AG has inodes in it and the AG is an
> exactly power-of-2 size then the last inode in the AG points
> to the last block in the AG. If we try to find the next inode
> in the AG by adding one to the inode number, we increment the
> inode number past the size of the AG. The result is that the
> macro XFS_INO_TO_AGINO() will strip the AG portion of the inode
> number and return an inode number of zero.
> 
> That is, instead of terminating the lookup loop because we hit the
> inode number went outside the valid range for the AG, the search
> index returns to zero and we start traversing the radix tree from
> the start again. This results in an endless loop in
> xfs_sync_inodes_ag().
> 
> Fix it be detecting if the new search index decreases as a result of
> incrementing the current inode number. That indicate an overflow and
> hence that we have finished processing the AG so we can terminate
> the loop.

Shouldn't this get merged into the patch that introduces the radix-tree
based sync?

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